切欠底の疲労強度の確率的変動に注目した高強度鋼切欠材の疲労強度特性に関する研究

概要

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This study was conducted to examine how and why a difference of fatigue strengths between un-notched and notched specimens, in terms of maximum stress amplitude at the notch bottom, depends on the change of hardness level in steel. As a result, the local fatigue strength of the notch bottom in the notched specimen became higher than that of the un-notched one with increase of notch sharpness and this was remarkable in high strength steel. This is because the transition of the fatigue fracture mode occurs from a slip induced crack initiation mode to a defect controled one with increasing hardness in steel. In addition, using a new experimental approach combined with a simulation technique based on the concept of risk competition of defects, a computer simulation was conducted on an effect of inclusion on the local fatigue strength at the notch bottom of high strength steel. It was clarified that the difference of fatigue strength between notched and un-notched specimens in high strength steel was caused by the statistical variation of the largest inclusion size contained in the critical volume at the notch bottom.
社団法人日本機械学会の論文
2005-04-25